Unipolar alternating-current machine.



No. 832,742. PATENTED OCT. 9, 1906.

J. E. NOBGGERATH.

UNIPOLAR ALTBRNATING CURRENT MACHINE.

2 sums-sum 1.

Wifnesses. Invent or; M$p JakobENoe Path; 1% by 711389.

No. 832,742; PATENTED OCT. 9, 1906.

a; B. ROBGGERATH. UNIPOLAR ALTERNATING CURRENT MACHINE.

APPLICATION FILED Ill. 1'], 1906.

2 SHEETS-SHEET 2.

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q; .Z Witnesses. G Inventor:

We. Jakob E. Noeggerath M W a W either as generator or motor.

atany UNITED STATES PATENT OFFICE.

JAKOB E. NOEGGERATH, OF SGHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY. A CORPORATION OF NEW YORK 1'0 whom it may Be it known that I, .Iaxoa EJNoaoome A111,! citizen of the United States, residing at Schenectad county of Schenectady, State of New 'ork', have invented certain new and useful Improvements in Uni lar Alternating-(31mm Machines, of whic the followingis a specification. r

M invention relates to gFnamo-electric mac es for operation on ternatingcurrents.

I have discovered that a machine of the unigolar type may be adapted by laminating its eld structure and properly proportioning and the several parts for efficient commercial operation on alternating current,

h arranged h d hi h nemtor tus tespee atw'c tearmature is driven has no effect upon the fre quency of the currents produced, but only upon the volta e. The frequency is determined absoluteFy by the frequency of alternation of the field flux. Such a generator h advantages for operation at ordinary frequencies as compared with machines of the usual construction, since there is no danger of its falling out of synchronism, as it,

has no synchronous speed, but will operate speed, delivering currents of a frequency etermined by the frequency of the current supplied to its field-coil. Such a machine is particularly advantageous for use with steam-turbines, since it renders it possible to obtain the usual commercial frequencies with as high a speed as desired. Furthermore, such a generator possesses the great advantage of rendering it possible to obtain commercially alternat' currents of exceedingly low frequencies, suc as three or four cyc es, frequencies which have been commercially unattainable with machines of the usual type. Similarly as a motor the 'machine may operate on a current of any frequency and at any speed. As a motor the machine will start under load and will operate sparklessl for all loads and speeds.

In its broa est aspect I claim as my invention an alternating-current dynamo-electric machine com a unipolar field structure provided Wit a Eeld-winding adapted for connection to a source of alternating current and a plurality of armature-conductors ar-.

ranged to be traversed by the flux of said uni.

polar field and relatively movable thereto,

Specification of Liam Patent;

laplleaflel m larch 11,10 0. s-u 1.. zoomsdescribed above.

the two armature hubs or b ies C C.

UNIPOLAR ALTERNATlNG-CUHREN'I' MACHINE;

mascot. 9,1906.

the field structure laminated in planes parallel to the armature-shaft.

My invention further comprises a number of structural features which assist in producmg an efficient machine of the general type These features will appear from the following specification and accompanying and will be more specificalli'npomted out in the appended claims;

,Figurelshowsacrosssectional side e evation of a machine arranged in accordance with my invention.

2 shows a cross-section of the field strucr ture on line 2 2 of Fig. 1. Fig. 3 shows an end elevation of one of the armatures, and Fig. 4 shows a di?rammatic development of the armatures an brush connections.

In the drawings, A represents the field structure, which is composed of laminations of magnetic material. In order that the field structure may be readily assembled, I form it of a plurality of sections, as shown in Fig. 2, each section consisting of a body of parallel laminations arranged in planes arallel with the shaft. These sections at t eir inner extremities are in contact with or near to each other, so as to form a substantially continuous magnetic This may be broken at one or two places, as indicated at a in Fig. 2, in order to prevent the circulation of eddy-currents, as will be hereinafter explained. The several sections, of which there are shown four in Fig. 2, extend radially outward, dive from each other, and are held t spaces tween the sections afl'ord convenient access to the collecting-brushes, as will hereinafter appear.

B Bin Fig. 1 represent the field or mag netizing coils.

E represents the armature-shaft, which is mounted in bearings e e at opposite ends of the machine. These bearings are made of non-m agnetic material, so as to prevent leakage of the field-flux through the shaft; Secured to the shaft near its op osite ends fie e hub C is provided with two clamping-rings 0, between which are clamped the armatureether by t e frame-pieces a a. Theconductors D, which are suitably insulated from the clamping-rings. The construction of the armature which I have shown resembles somewhat that of the commutatoron a direct-current machine. This construction is sho matur -conductors D are, sector-shaped and radially arranged in -a solidymassand are made of magnetic material, suchas iron or steel. With-the laminated field-body A the armature-conductors form a nearly-closed magnetic circuit for the flux of the field-coil B. A similar path through the armatureconductors D is formed at the posite end of the machine for the flux of the eld-coil B. Since the-air-gaps between the armature-con:

' ductors D and the field structure A are radial, they may be made much shorter than in a machine as ordinarily constructed, since it is 7 and B are properly connected, the electromotive'force induced in the conductorsD maybe radially inward at the instantthat the electromotive'force induced in the con ductors D is radially outward. Conse quently it ispossible to place a conductor D in series with the conductor D by connecting their inner ends. Such connections are shown at g in Fig. 1. These conductors ma be a supported in a member G, keyed to the s aft.

In order to reduce magnetic leakage from the 5 field structure A to the shaft, this member may be made of non-magnetic material.

F and F represent brushes bearing on the outer ends of the conductors D and D, re-

s actively, all collecting devices intermediate the conductors and the brushes being disensed with in the arrangement shown. .gince the conductors D and D are connected in series, as has been heretofore explained, an electromotive force exists between the brush F and the brush F, bearing on the corresponding conductors equal to the electromotive force of twoconductors. The terminal voltage of the machine may be made as high as desired by connecting'brushes at opposite ends of the machine in series. This connec-, tion is preferably made by means of conductors h, which are placed in holes or slots at or near the inner periphery of the field structure A. The conductors h and g serve mutually to neutralize the others self-induction. The inner eriphery ofstructure A is shown slotted in ig. 2 at h inorder to receive these return-conductors.

Fig. 4 shows a development of the two armatures and their connections. The field- 4 coils are indicated at B and in this case are shown connected to an auxiliary exciter' b, supplying alternating current. The'two sets n in and elevation in 'The ar- If the field-coils B.

bearing on the peripheryofthe conductors. The connections 9, permanently connecting opposite conductors, are shown in full lmes,

while the return-conductors 72-, supported by the frame, are shown in dotted lines. Twelve sets of brushesare shown on each armature.

Since the brushes are all connected in series, a terminal voltage equal to twenty-fourtimes the induced voltage of one conductor is obtained. The terminal voltage may be varied as desired by varying the relative connections of the brushes. I

For the sake of simplicity each return-conductor in Fig. 4 is shown connectin a brush to the next to the opposite brus .on the other armature. This arrangement obviously produces such a distribution of potential on each armature that the maximum voltage of the armature exists between two adjacent brushes. This would be undesirable in practice, and accordingly the connections would ordinarily be arranged sothat the maximum potential would exist between opposite or nearly opposite points on each armature. Such a change in the connections Will; be? obvious to -thoseskilled in the art.

I A machine of the character described may be self-excited or separately excited, and if self-excited may be shunt, series, or compound. When self-excited, it of course requires, like other asynchronous generators,

-a synchronous machine connected to the same system to determine the frequency. While only a portion ofthe armature-conductors are at any instant incircuit, the current density for this reason may be high, so' that the same output per unit of weight may be obtained as if all the armature-conductors were all the time in circuit. g

It will be seen that since the armature-conductors are all revolving in a uniform field the electromotive forces induced in all the conductors will be equal. Consequently there can be no short-circuit currents under the brushes at any time, and sparkless operation is therefore secured. Moreover, the variations in current in adjacent conductors in passing under a brush are such that the selfinduction is mutally neutralized.

' Since the field flux is parallel to the shaft, it

that theelectric continuity of all conductors surrounding the shaft should be interrupted. Thus, for instance, if collector-rings are employed between the conductors and brushes the electrical continuity of the rings must be -is essential in order to prevent eddy-currents 1 interrupted. It is for this reason that the continuity of the ring forming the unipolar field is interrupted by air-gaps a as shown in Fig. 2. Since the revolving disk armatures are formed of separate conductors, eddy-currents are prevented by suitable insulation placed between adjacent conductors, as in the construction of an ordinary commutator.

It will be obvious that my invention comto this particularform of armature. Accordingly I do not desire to limit myself to the particular construction and arrangement of parts here shown, but aim in the a nded claims to cover all modifications w ch are within the scope of my invention;

What I claim as new, and desire to secure by Letters Patent of the States, is 1. An alternating-current dynamo-electric machine, com rising a field structure arranged to pro uce a unipolar field, a fieldwinding adapted to be connected to asource of alternating current, and a plurality of armature-conductors arranged to be traversed by the flux of said unipolar field and relatively movable thereto, said field structure being laminated in planes parallel with the armature-shaft.

2. In a field structure for d mo-electric machines, a plurality of re iall -arranged wctions, each com of paral el laminations, said sections ving their inner ends in close proximity to each other so as to form a unipo ar field. 4

3. In a field structure f0 d amo-electric machines, a plurality of all -arranged sections, each com of paral e1 laminations, said sections aving their inner ends in close proximity to each other and forming a substantially continuous ring of laminated magnetic material.

4. In a field structure for d amo-electric machines, a plurality of iall -arranged sections, each com of paral el laminations, said sections ving their inner ends in close proximity to each other and forming a substantially continuous ring of laminated magnetic material, and a magnetizing-coil concentric with said ring.

Y 5. In an alternating-current dynamo-electric machine, a field structure comprising a plurality of radial] -arranged sections, each composed of l laminations, said sections having their inner ends inclose proximity to each other so as to form a unipolar field, and a m t' -coil concentric with theshaft of t e r n ifiine connected to a source of alternating current.

6. In an alternating-current d o-electric machine, a unipolar field structure formed of laminations in planes parallel with the shaft, and a old-winding connected to a source of alternating current.

7. In an alternating-current dynamo-electric machine, a unipolarfield structure fonned of laminationsgarranged in planes parallel with the shaft, and a field-coil concentric with the shaft, and connected to a source of alternating current.

' 8. In a dynamo-electric machine, a revolving armature com risi 'a lurality of radiall -arranged cor iduc t rs o? magnetic materia and a field structure laminated in planes arallel with the armature-shaft and ads ted to produce a unipolar flux threading sai conductors in an axial direction.

9. In a dynamo-electric machine, a revolving armature comprising a plurality of radially-a d conductors of m etic materia, a fiel structure lamina in lanes parallel with the armature-shaft and apted to produce a unipolar flux threading said conductors in an axial direction, and collectinghrushes'bearing on the outer ends of said conductors.

10. In a dynamo-electric machine, two sets of radiall -arranged conductors of m netic materia carried by the shaft, a fie dstructure arranged to produce two uni larfield fluxes threading said two sets oi izonductors respectively in an axial direction and connections between theinner ends of conductors of opposite sets.

11. In a dynamo-electric machine, two

' sets of radial] -arraljed I conductors of m netic material carri by the shaft, a fizFd structure to produce two uni larfield fluxes threading said two sets 0 conductors respectively in an axial direction, connections between the inner ends of conductors of opposite sets, and two sets of brushes bearing on the outer ends sets of conductors respectively.

12. In a, dynamo-electric machine, two

sets of radial] 'arrare1g1ed conductors of netic material carri by the shaft, a fie d structure arranged to produce two unipolarfield fluxes threading said two sets 0 conductors respectively in an axial direction, connections between the inner ends of conductors of o posite sets, two sets of brushes bearing on the outer endsof the two sets of conductors respectively, and connections be tween brushes of o posite sets, said connections being carried by the field structure adjacent to the first-mentioned connections.

13. In a dynamo-electric machine, a revolving armature comprising a plurality of rulially-arranged sector-shaped of magnetic material boun together in. a solid mass, and a field structure laminated in planes arallel with the armature-shaft and ads to to produce a unipolar flux threading sai conductors in an axial direction.

14. In a dynamo-electric machine, a revolving armature comprising a plurality of radially-a conductors, a field structure com 0:

of the two v conductors winding connected to an alternating-current.

source.

15'. In a dynamo-electric machine, two sets of radially-arranged conductors carried by the shaft, a-field structure arranged to produce two unipolar-field fluxes threading said two sets of conductors respectively in an axial direction, connections between the inner ends of conductors of opposite sets, two sets of brushes bearing on the. outer ends of v the two sets of conductors res ectively, and

" natingcurrent, and conductors connecting the inner ends of armature-conductors of opposite sets. v

17. In a d namo-electric machine, two sets of radiall y-arranged armature-conductors carried by the shaft, a laminated field structure adapted to produce two unipolar fields threading said conductors espectively,

30 a field-winding connected to a source of alterscam nating current, conductors connecting the inn-er ends of armature-conductors of opposite sets, two sets of collecting-brushes in electrical contact with the outer ends of said armature-conductors res ectively, and con- 3 ductors' carried by the old structure adjacent to said connecting-conductors and con-- necting-brushes of opposite sets.

184A dynamo electric machine com rising field structure and armature bot magnetic material laminated in planes arallel with the armature-shaft and sai field structure being arranged to produce a unipolar field, and a field-winding adapted to be connected to a source of alternating current. 45

19 In a dynamo-electric machine, an armature com rising a pluralit of radially-arranged con uctors, brushes caring directly on said conductors at or nearv their outer ends, and a field structure laminated in 50 planes. arallel with the armature-shaft and ada ted to produce aunipolar flux threading sai conductors in an axial-direction.

In witness whereof I have hereunto set my hand this 15th day of March, 1905.

- JAKOB E. NOEGGERATH.

Witnesses:

BEN AMIN B. HULL, HELEN ORFORD. 

